An organic light emitting diode (OLED) is a semiconductor device that can convert electrical power into optical lighting. OLEDs offer high conversion efficiency, self-emission, ultrathin structure, high luminance, high luminous efficiency, high contrast ratio, short response time (can be as short as several microseconds), extra wide viewing angle, low power consumption, wide operating temperature range, and panel flexibility therefore are broadly applied to many different electronic products.
Some conventional techniques for fabricating flexible environmentally sensitive electronic element packages through a roll-to-roll process have been provided, such as those disclosed in the U.S. Pat. Nos. 6,888,172 B2, 6,949,825 B1, and 7,135,352 B2. However, some other conventional techniques that do not use the roll-to-roll process for fabricating environmentally sensitive electronic element packages are also provided, such as the one disclosed in U.S. Pat. No. 6,803,245 B2.
An encapsulation method for fabricating flexible environmentally sensitive electronic elements is disclosed in U.S. Pat. No. 6,803,245 B2, wherein flexible environmentally sensitive electronic element packages are fabricated by using a substrate holder and a cover lid holder. However, in this technique, the cover lid holder and a cover lid have to be fastened together by using an adhesive tape, and the cover lid and a substrate on which environmentally sensitive electronic elements are disposed are aligned with each other according to an alignment mark on the substrate holder and an alignment mark on the cover lid holder. However, when the cover lid is placed on the cover lid holder and the substrate having the environmentally sensitive electronic elements is placed on the substrate holder, alignment accuracy is an important issue of mass production. Accordingly, imprecise alignment may likely be produced when the cover lid and the substrate are bonded together. As a result, the fabrication yield of the product may be affected. Besides, the heating process carried out during the fabrication process may cause the adhesive tape to lose its adhesiveness. As a result, the reliability of the fabrication process may be affected.